var casper = require('casper').create({
    verbose: true,
    logLevel: 'debug'
});
casper.log('plop', 'debug');
casper.log('plip', 'warning');
casper.log('this is a debug message', 'debug');
casper.log('and an informative one', 'info');
casper.log('and a warning', 'warning');
casper.log('and an error', 'error');
casper.exit();